1. Field of the Invention
This invention relates to a method of running an internal combustion engine with a high compression ratio on low octane gasoline, and more specifically, to running an internal combustion engine with a high compression ratio on low octane gasoline by always starting the compression stroke with the charge at less than atmospheric pressure.
2. Description of the Prior Art
The compression ratio that can be used in internal combustion engines is limited by the pre-ignition firing temperature in spark ignition engines, and by the maximum pressure which can be withstood in compression ignition engines. As lower octane fuels have come into widespread use, compression ratios have been lowered to ensure that fuel temperature during the compression stroke does not exceed the pre-ignition firing temperature. Typically, spark ignition engines today are run at a compression ratio of approximately 8:1, with a pressure at ignition of approximately 170 psia. However, higher compression ratios result in greater engine efficiency and improved mileage. Compression ignition engines also have greater efficiency at higher compression ratios.